Projection weld and method for creating the same

ABSTRACT

Disclosed is a projection welding method including providing a first metal substrate, a second metal substrate, and a projection material of separate construction from the first metal substrate and the second metal substrate, disposing the metal projection material between the first metal substrate and the second metal substrate, applying a current and pressure to at least one of the first metal substrate and the second metal substrate, melting the metal projection material via the application of the current and pressure, creating a weld between the first metal substrate and the second metal substrate via the melting, and fixedly associating the first metal substrate and the second metal substrate via the weld.

FIELD OF THE INVENTION

The disclosure relates generally to a method of welding, and moreparticularly to a method of projection welding.

BACKGROUND

Projection welding is a known technique for joining two overlappingmetal sheets. In conventional projection welding, a small projection isprovided on one of the sheets and extends transversely to a side of thesheet so that the tip thereof contacts the other sheet. A currentproducing device (such as an electrode of a welding gun) is pressed intocontact with one of the sheets in alignment with the projection, and acombination of force and welding current is applied to the electrode tocause the projection to collapse and form a weld nugget which joins thetwo sheets together at the contact area defined by the projection.

Resistance projection welding is a solid state joining method, whicheliminates the need for pre-heat that arc-welding methods require.Projection welding is also fast, which reduces manufacturing time.However, the properties of some metals render theses metals incapable ofbeing directly welded to each other via this process. In addition,joints are very difficult to form in highly conductive materials, suchas copper. Heat is conducted away from the joints rapidly, producingjoints with defects. In welds, this can lead to lack of fusion andporosity. None-the-less, copper joints are essential in manyapplications, particularly in the magnetic coils of MRI equipment. Thus,there is a need for a more efficient forming of joints, and means forprojection welding metals that are incapable of being directly welded toeach other.

BRIEF DESCRIPTION OF THE INVENTION

Disclosed is a projection welding method including providing a firstmetal substrate, a second metal substrate, and a projection material ofseparate construction from the first metal substrate and the secondmetal substrate, disposing the metal projection material between thefirst metal substrate and the second metal substrate, applying a currentand pressure to at least one of the first metal substrate and the secondmetal substrate, melting the metal projection material via theapplication of the current and pressure, creating a weld between thefirst metal substrate and the second metal substrate via the melting,and fixedly associating the first metal substrate and the second metalsubstrate via the weld.

Also disclosed is a projection weld including a first metal substrate, asecond metal substrate, a projection material separate from the firstmetal substrate and the second metal substrate, and a projection weldnugget including a mixture of the first metal substrate, the secondmetal substrate and the projection material.

Further disclosed is a projection welding method including providing afirst metal substrate, a second metal substrate, and a metal projectionmaterial of separate construction from the first metal substrate and thesecond metal substrate, affixing the metal projection material to thefirst metal substrate, disposing the second metal substrate with theprojection material and the first metal substrate such that theprojection material is disposed between the first metal substrate andthe second metal substrate, applying a current and a pressure to atleast one of the first metal substrate and the second metal substrate,melting the metal projection material via the application of the currentand the pressure, creating a weld between the first metal substrate andthe second metal substrate via the melting, and fixedly associating thefirst metal substrate and the second metal substrate via the weld.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numberedalike:

FIG. 1 is a schematic side perspective view of an exploded projectionweld in accordance with an exemplary embodiment;

FIG. 2 is a schematic side perspective view of elements of a projectionweld receiving a current;

FIG. 3 is a schematic side view of a projection weld;

FIG. 4 is a schematic side view of multiple projection welds; and

FIG. 5 is a block diagram illustrating a method of projection welding.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-3, a projection weld 10 is illustrated and includesa first metal substrate 12, a second metal substrate 14, and a metalprojection material 16. As is shown in the Figures (particularly in FIG.3) the metal projection material 16 fixedly associates the firstsubstrate 12 with the second substrate 14 via projection welding. Anexemplary embodiment of the manner by which this welding occurs will bedescribed hereinbelow.

Referring to FIG. 1, the components of the projection weld 10 areillustrated prior to being welded. As is shown in the Figure, the firstsubstrate 12, second substrate 14, and projection material 16 are all ofseparate construction from each other. The first and second substrates12 and 14 may be any metals (or multiple alloys) of the same ordifferent compositions, such as but not limited to carbon, steel,aluminum, and copper. In an exemplary embodiment, these substrates 12and 14 are substantially planar sheets, as shown in the Figures. Theprojection material 16 may also comprise any metal or multiple alloys ofany desired composition, and be formed of wire, meshed wire (either ofwhich may be cored or coated with flux), powder, or any other desirablematerial. In one exemplary embodiment a projection material of silvermesh is disposed between substrates of steel and aluminum. The form andmetallic composition of the projection material 16 is selected toprovide a strong projection weld between the first and second substrates12 and 14, based on the properties of the first and second substrates 12and 14. The projection 16 may also include any desirable shape, such asbut not limited to a truncated cone or partial sphere.

Referring to FIG. 2, once the projection material 16 is selected andplaced between the substrates 12 and 14, both substrates 12 and 14 maybe brought into contact (or nearly into contact) with the projection 16in preparation for projection welding the substrates 12 and 14. Thiscontact (or near contact) occurs at opposite ends 18 and 20 of theprojection 16 (see FIG. 1), with the ends 18 and 20 respectivelycontacting relative inner surfaces 22 and 24 of the first and secondsubstrates 12 and 14. Projection welding may then be accomplished viaapplication of a current 26 and pressure 36 to at least one of thesubstrates 12 and 14. In the exemplary embodiment of FIG. 2, the current26 and pressure 36 are applied to both substrates 12 and 14 viaelectrodes 28 and 30. In this embodiment, the electrodes 28 and 30 arealigned with the projection substrate 16, and thus, provide the currentin alignment with the projection 16. As mentioned above, the electrodes28 and 30 also provide pressure to the substrates 12 and 14, again inalignment with the projection 16, which further expedites the projectionwelding process.

Referring now to FIG. 3, providing the current 26 and pressure 36 to thesubstrates 12 and 14 creates a weld 32 that completely melts theprojection material 16. This weld 32, created via heat generated by thecurrent 26 and pressure 36, forms a projection weld nugget 33 thatincludes a mixture of the substrates 12 and 14 and projection material16. The weld 32 fixedly associates the first substrate 12 and secondsubstrate 14 via the projection welding process.

It should be appreciated that prior to application of the current 26 toat least one of the substrates 12 and 14, one end 18 or 20 of theseparately constructed projection 16 may be first fixed to one of thesurfaces 22 or 24 via any desirable means, such as but not limited toconventional welding. The other of the surfaces 22 or 24 may then bedisposed in proximity to (or in contact with) the other of the ends 18or 20, and the current 26 and pressure 36 may be applied. As above, thecurrent 26 and pressure 36 will then create a weld that will completelyconsume projection material 16. Thus, it should be appreciated that aprojection (such as projection 16) would be contemplated to be ofseparate construction from the substrates 12 and 14, even when theprojection 16 is fixed to one or both of the substrates 12 and 14 priorto application of the current and pressure (i.e. prior to creation ofthe projection weld nugget 33), as is discussed above with reference toone of the substrates 12 and 14. The projection 16 may also comprise thesame composition as one or both of the substrates 12 and 14, and beconsidered to be of separate construction from the substrates 12 and 14,regardless of whether or not the projection 16 is fixed to one or bothof the substrates 12 and 14 prior to application of the current andpressure.

Referring to FIG. 4, it should be additionally appreciated that thesubstrates 12 and 14 may be welded together via a plurality of welds 10created via the projection welding processes described above. Theplurality of welds 10 includes a plurality of projection material pieces16 spaced from each.

Referring to FIG. 5, a method 100 of projection welding is illustratedand includes providing a first metal substrate 12, a second metalsubstrate 14, and a projection material 16 of separate construction fromthe first metal substrate 12 and the second metal substrate 14, as shownin operational block 102. The method 100 further includes disposing themetal projection material 16 between the first metal substrate 12 andthe second metal substrate 14, applying a current and pressure to atleast one of the first metal substrate and the second metal substrate,and melting the metal projection material 16 via the application of thecurrent and pressure, as shown in operational block 104. The method 100also includes creating a weld 32 between the first metal substrate 12and the second metal 14 substrate via the melting, and fixedlyassociating the first metal substrate 12 and the second metal substrate14 via the weld 32, as shown in operational block 106.

While the invention has been described with reference to an exemplaryembodiment, it should be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor substance to the teachings of the invention without departing fromthe scope thereof. Therefore, it is important that the invention not belimited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the apportionedclaims. Moreover, unless specifically stated any use of the terms first,second, etc. do not denote any order or importance, but rather the termsfirst, second, etc. are used to distinguish one element from another.

1. A projection welding method, the method comprising: providing a firstmetal substrate, a second metal substrate, and a projection material ofseparate construction from said first metal substrate and said secondmetal substrate; disposing said metal projection material between saidfirst metal substrate and said second metal substrate; applying acurrent and pressure to at least one of said first metal substrate andsaid second metal substrate; melting said metal projection material viasaid application of said current and pressure; creating a weld betweensaid first metal substrate and said second metal substrate via saidmelting; and fixedly associating said first metal substrate and saidsecond metal substrate via said weld.
 2. The method of claim 1, whereinsaid metal substrates are of the same base alloys.
 3. The method ofclaim 1, wherein said first metal substrate is steel and said secondmetal substrate is aluminum.
 4. The method of claim 3, wherein saidmetal projection material is a silver or copper alloy
 5. The method ofclaim 1, wherein said metal substrates are of different base alloys. 6.The method of claim 1, wherein said metal projection material is atleast one of a wire, mesh, and powder.
 7. The method of claim 6, whereinsaid metal projection material is at least one a wire and a mesh,wherein said mesh is comprised of mesh wire, said wire and said meshwire being at least one of cored and flux coated.
 8. The method of claim1, wherein said metal projection material comprises multiple alloys. 9.The method of claim 1, wherein said first metal substrate and saidsecond metal substrate are substantially planar, and said metalprojection material is a plurality of projection material pieces spacedfrom each other.
 10. A projection weld comprising: a first metalsubstrate; a second metal substrate; a projection material separate fromsaid first metal substrate and said second metal substrate; and aprojection weld nugget including a mixture of said first metalsubstrate, said second metal substrate and said projection material. 11.The weld of claim 10, wherein said first metal substrate is steel andsaid second metal substrate is aluminum.
 12. The weld of claim 11,wherein said metal projection material is a silver or copper alloy 13.The weld of claim 10, wherein said first metal substrate and said secondmetal substrate are copper.
 14. The weld of claim 10, wherein said metalprojection material is at least one of a wire, mesh substrate, andpowder.
 15. The weld of claim 14, wherein said metal projection materialis at least one a wire and a mesh substrate, wherein said mesh iscomprised of mesh wire, said wire and said mesh wire being at least oneof cored and flux coated.
 16. The weld of claim 15, wherein said metalprojection material comprises multiple alloys.
 17. The weld of claim 14,wherein said first metal substrate and said second metal substrate aresubstantially planar.
 18. A projection welding method, the methodcomprising: providing a first metal substrate, a second metal substrate,and a metal projection material of separate construction from said firstmetal substrate and said second metal substrate; affixing said metalprojection material to said first metal substrate; disposing said secondmetal substrate with said projection material and said first metalsubstrate such that said projection material is disposed between saidfirst metal substrate and said second metal substrate; applying acurrent and a pressure to at least one of said first metal substrate andsaid second metal substrate; melting said metal projection material viasaid application of said current and said pressure; creating a weldbetween said first metal substrate and said second metal substrate viasaid melting; and fixedly associating said first metal substrate andsaid second metal substrate via said weld.
 19. The method of claim 18,wherein said affixing of said metal projection material to said firstmetal substrate is accomplished via welding.